The present invention relates to optical probes for non-intrusive stress measurement systems (NSMS), and more specifically relates to a high temperature optical probe for a NSMS.
In the gas turbine engine, temperatures in the low pressure compressor can reach 400 degrees Fahrenheit. Temperatures in the high pressure compressor can reach 1200 degrees Fahrenheit. Current probes can only withstand temperatures of 350 to 400 degrees Fahrenheit due to temperature limitations of the optical fibers, lenses, and adhesive used to hold the probes together. As a result, current probes require cooling passages for coolant flows in order to cool the probes to 350 degrees Fahrenheit to prevent the probes from burning up in the high and low pressure compressors. Cooling flows are costly, as cooling the probes requires a significant amount of gaseous nitrogen (GN2). Coolant flowing from the probes may also cause problems with bleed flows in engine cavities, such as causing bleed flows to reverse direction. Additionally, inclusion of cooling passages increases the size of the probes, limiting where the probes can be placed within the engine.